The goal of this proposed project is to demonstrate evidence for the time-limited, hippocampal-dependent consolidation of a cortical memory representation. Current theory suggests that the storage of long- term, declarative memories is dependent on interactions between the hippocampal system and neocortex. With the passage of time, memory representations become less dependent on the hippocampal system, until they become permanently consolidated in neocortex. This project will address this goal using electrophysiological and behavioral assessment in an 8-odor serial discrimination task with predictive relationships between odors. The specific aims are: (1) To analyze the development of changes in the firing patterns in OF associated with learning of predictive relationships between odors (i.e., learning stimulus-stimulus pairing in which the first of two stimuli predicts the ensuing occurance of the second), both at the level of the single unit and at the level of the neural ensemble. (2) To demonstrate that the behavioral and electrophysiological correlates associated with learning of predictive relationships are dependent on the hippocampal system. (3) to study the time course of the consolidation of these same cortical representations as they gradually become independent of the hippocampal system. This hypothesis will be tested by giving rats ibotenate lesions of the hippocampal region at varying times after learning the predictive relationships between odors, and by reversibly inactivating the hippocampal region with muscimol at varying times during performance of the memory task.